Gale Warning 245, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
254 PM AKST Fri Nov 10 2017

.SHORT TERM...Through Sunday night...Warm air advection with the
current front was a little stronger than expected today resulting in
overrunning snowfall setting up further north than predicted.
Pelican, Gustavus, Hoonah, and Juneau all ended up with temps around
35 degrees for most of the day with the western three towns
reporting rain. It was not until mid afternoon that northerly winds
started to strengthen enough to get colder air back into these areas
and change the ptype back to snow. By that point, however, precip
was on the decreasing trend for most areas and temps remained above
freezing. The winter storm warnings were cancelled earlier in the
day. Juneau still has a longer period of precip expected this
evening so kept a winter weather advisory going for that area
through the evening. Meanwhile, Haines was the area that got the
overrunning snowfall with moderate snow reported most of the day.
Skagway got on the northern edge. Coop and Spotter reports showed
around 3.7 inches at Haines and around 2 inches in Skagway as of 2
pm. Winter weather advisory continues for Haines this evening.

Tonight and Sat feature a shift to the south and east and a
diminishing trend for the precip. Most areas south of Hoonah will
be too warm for snow with the exceptions being Petersburg (where
a winter weather advisory remains up for this evening) and Hyder
(which will not receive more then a few inches). The north will be
rapidly drying out tonight and Sat as cold air outflow starts up
again. Gale force winds expected in Lynn Canal and Cross Sound as
early as late tonight with gusts to 40 or 45 mph expected at Skagway
and other outflow areas. Northerly outflow winds will penetrate all
the way to the southern panhandle by Sat night with many marine
areas expected to see 25 to 30 kt northerlies by that time. Another
mountain wave event is also possible for downtown Juneau and Douglas
Sat night. Outflow expected to last through Sun before diminishing
Sun evening.

Guidance was a little too weak with the warm air advection into
the inner channels today but was good overall with precip
intensity timing and low track. Most changes confined to local
effects for winds and ptype. GFS and NAM used for overall guidance.

.LONG TERM...Sunday through Friday...The general pattern for the
long term Sunday through Friday will be a series of low pressure
systems in the Gulf interacting with high pressure ridges or
systems located across the Yukon. The high pressure areas will
weaken and strengthen at times. Therefore the pressure gradient
will tighten across the panhandle when a stronger low pressure
system in the Gulf interacts with a stronger high pressure area
to the north. Winds will increase during these times.

A shortwave will move into the Gulf Sunday and a low pressure
system near Haida Gwaii will move North. The higher precipitation
areas will be across the southern areas of the panhandle Sunday.
Precipitation will gradually spread northward on Monday.

Shortwaves moving within a deepening upper level low pressure
trough will spread colder air across the panhandle. Therefore
temperatures will continue below the seasonal average Sunday
through Friday. Strong outflow winds will likely produce gale to
storm force winds during the strongest outflows.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Winter Weather Advisory until midnight AKST tonight for
AKZ025-     026.
     Strong Wind Saturday afternoon for AKZ025.
     Winter Weather Advisory until 6 PM AKST this evening for AKZ019.
     Strong Wind from 9 PM AKST this evening through Saturday
     afternoon for AKZ018.
MARINE...Gale Warning for PKZ012-013-022-043-051.
     Small Craft Advisory for PKZ011-021-031>034-042-052-053.
     Small Craft Advisory due to Seas for PKZ041.

&&

EAL/BM

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